Aspects of the present invention relate to dispersion of a signal during transmission. More specifically, it is related to monitoring of bulk dispersion of an optical signal in an optical fiber. Bulk dispersion is used generally to mean a large level of dispersion such as that which would arise in a long length, such as many kilometers, of optical fiber, or an entire link (a length of fiber between two nodes) or several links of fiber.
Dispersion is commonly dependent on a length of a transmission path, dispersion parameters associated with the fibers within the signal path (typically expressed in ps/nm/km), and some other properties of the transmission path. Many optical systems require dispersion compensation either optically, using special types of optical fibers or optical devices, or, electronically at the receiver. Dispersion compensation requires knowledge of the amount of bulk dispersion accumulated by the signal. Although bulk dispersion can be measured for a fixed link, it becomes path-dependent in dynamically reconfigurable and wavelength routed systems where the signal path can change rapidly in time. When an optical network is reconfigured, new values of bulk dispersion must be established as the total length and a particular dispersion of the fiber change. Current methods typically require a certain amount of computation time, which is often far too long for a rapid reconfiguration. Currently, there is no solution to measure >1 ns/nm dispersion for >40 Gb/s signals using only the signal itself, especially when the signal carries live traffic. A current system using 100G data and measuring eye closure on cush signals would be limited to several 100 ps/nm of dispersion before the eye closure would become too great for further quantification of the dispersion penalty
Accordingly, improved methods and apparatus to determine and monitor bulk signal dispersion that overcome the above limitations of the prior art are desired.